The invention relates to an optical transmission system comprising an optical transmitter coupled over an optical channel to an optical receiver, the optical receiver comprising an optoelectrical converter and an amplifier while a first connection terminal of the optoelectrical converter being coupled to a first input of the amplifier.
The invention likewise relates to an optical receiver to be used in a system of this type.
A transmission system as defined in the opening paragraph is known from the brochure "2610 B Broadband Photodiode Module", Ortel Corporation, May 1991.
Such a transmission system is used, for example, for TV signal distribution over large distances. This takes place, for example, in cable TV networks for TV signal transmission from a remote header station to a cable TV main distribution network.
The cable TV signal to be transmitted, comprising a frequency multiplex of TV and radio signals, is used for amplitude modulation of a light source. The light source will generally comprise a semiconductor laser. The modulated light signal is sent over an optical channel, for example, a glass fibre, to the optical receiver. In the optical receiver the light signal is converted into an electric signal which can be further distributed in the cable network.
The cable TV signal has a frequency range from .+-.80 MHz to 900 MHz. This means that the transmission system must to be suitable for broadband signals, meaning the aforesaid range. A requirement frequently made on such transmission systems is a passband which is flat within several tenths of dB's or increases with a certain slope with increasing frequency.
Although the transfer characteristic of the prior-art optical transmission system is flat within 1 dB, a flatter transfer characteristic is desired.
It is an object of the invention to provide an optical transmission system as defined in the opening paragraph in which the flatness of the transfer characteristic is improved.